The effective, economical, and environmentally sound control of grass weeds in growing crops is a major problem for farmers. Weeds cost farmers billions of dollars annually in crop losses and in the expense of keeping the weeds under control. The losses caused by weeds in agricultural production environments include decrease in crop yield, reduced crop quality, increased irrigation costs, increased harvesting costs, decreased land value, injury to livestock, and crop damage from insects and diseases harbored by these weeds.
Those skilled in the art are continuously attempting to find better methods to control grass weeds in growing crops. One such method is the administration of the acetyl coA carboxylase inhibitor herbicides such as sethoxydim, clethodim, quizalofop-p-ethyl, fluazifop-p-butyl, fenoxaprop-p-ethyl and caloxydim (developmental cyclohexenone). See, Herbicide Handbook--Weed Science Society of America--Seventh Edition, 1994. Further, the art teaches the administration of these herbicides alone or in conjunction with other herbicides having a different mechanism of action other than acetyl coA carboxylase inhibition. Specifically, the following publications all disclose that sethoxydim or clethodim are effective at standard lethal doses in controlling grass weeds in growing crops: Growth Stage Comparison of Postemergence Herbicides on Three Grass Species, Snipes, C. E.; Lantham, D. J.; Bulletin--Mississippi Agricultural and Forestry Experiment Station, (1994), No. 1015, pp. 7; The Effect of Giant Foxtail (Setaria faberi) Plant Height on Control With Six Postemergence Herbicides, Krausz, R. F.; Kapusta, G.; Matthews, J. L.; Weed Technology, (1993) Vol. 7, No. 2, pp. 491-491; Efficacy and Economics of Common Bermuda Grass (Cynodon dactylon) Control in Peanut (Arachis hypogaea); Wilicut, J. W.; Peanut Science, (1991) Vol. 18, No. 2, pp. 106-109; Johnsongrass (Sorghum halepense) Control in Soybeans (Glycine max) With Postemergence Herbicides; Johnson, W. G.; Frans, R. E.; Weed Technology, (1991) Vol. 5, No. 1, pp. 87-91; Herbicides for Control of Mercer Grass (Paspalum distichum) in Asparagus; Rahman, A.; Sanders, P.; Asparagus Research Newsletter, (1991) Vol. 8, No. 2, pp. 20-23; Control of Texas Panicum (Panicum texanum) and Southern Crabgrass (Digitaria cillaris) in Peanuts (Arachis hypogaea) with Postemergence Herbicides; Grichar, W. J.; Peanut Science, (1991) Vol. 18, No. 1, pp. 6-8; Wild-Proso Millet (Panicum miliaceum) Control in Soyabeans (Glycine max) with Postemergence Herbicides; Harvey, R. G.; Porter, D. J.; Weed Technology, (1990) Vol. 4, No. 2, pp. 420-424; Herbicides for the Control of Mercer Grass (Paspalum distichum) in Asparagus; Rahman, A.; Sanders, P.; MAF Technology North, Ruarkura Agricultural Centre, Private Bag, Hamilton, New Zealand. (1990) pp. 48-51; Grass Control Herbicides in Soybean; Skrzypczak, G. A.; Wright, D. L.; Proceedings, Soil and Crop Science Society of Florida, (1988) Vol. 47, pp. 150-157. However, their use together at synergistically effective amounts is not disclosed.
Additionally, the synergistically effective administration of two herbicides having different mechanisms of action is disclosed. See, U.S. Pat. No. 5,108,488 assigned to Valent that discloses the postemergent administration of a composition comprising synergistically effective amounts of clethodim and flumioxazin, a primarily broadleaf weed herbicide; U.S. Pat. No. 5,238,901 assigned to Sumitomo that discloses the preemergent application of a composition comprising synergistically effective amounts of flumioxazin, a primarily broadleaf weed herbicide, and alachlor; U.S. Pat. No. 4,517,009 assigned to FBC, Limited that discloses the postemergent administration of a composition comprising synergistically effective amounts of benazolin and acifluorfen; U.S. Pat. No. 4,378,990 assigned to Schering AG that discloses the postemergent administration of a composition comprising synergistically effective amounts of 5-(N-phenyl carbamoylamino) 1,2,3-thiadiazole and a phenyl ether; and U.S. Pat. No. 5,047,080 assigned to Sumitomo that discloses the postemergent administration of a composition comprising a synergistically effective amount of flumioxazin, a primarily broad leaf weed herbicide, and sethoxydim or alloxydim.
The existing art also teaches that two acetyl coA carboxylase inhibiting herbicides can be effective on grass weeds when blended together at their full lethal dosage rates. An example of this is FUSION.RTM., which is a premix of fluazifop-p-butyl and fenoxaprop-p-ethyl.
However, the art does not teach or suggest that two herbicides, having the same mechanism of action, i.e., acetyl coA carboxylase inhibiting herbicides effective on grass weeds, can be blended together in sub-lethal amounts in a tank mix, and applied at these sub-lethal amounts to provide effective control of grass weeds in growing crops. Thus, Applicants' discovery that sub-lethal amounts of two acetyl coA carboxylase inhibiting herbicides provide effective grass weed control is an unexpected advance in the herbicide art.